1. Field of the Invention
The present invention relates to a needle assembly and more particularly concerns a self-venting, non-coring needle assembly for the transfer of liquid to or from a container having a needle penetrable stopper thereon.
2. Description of the Prior Art
Liquid medication, for injection and intravenous applications, is commonly available in rigid containers having a closure with an elastomeric needle penetrable stopper. Frequently the amount of liquid medication in these containers is in excess of the amount required for each individual dose. Accordingly, it is the task of a hospital pharmacy, for example, to transfer the liquid medication from the larger container to smaller containers, also with needle penetrable stoppers, such as I.V. bottles or to other storage or delivery devices such as syringes. This type of transfer is also required where the medication has a short shelf life and must be mixed just prior to use, for example using a syringe for adding sterile water to a vial containing lyophilized medication. Since sterility of the medication is desired, the vial to vial, syringe to vial, or vial to syringe transfer is usually performed in a laminar flow hood. Transfer of liquid medication to and from these vials requires not only piercing the stopper to provide a path for the medication but also piercing the stopper to provide a path for air to escape or enter the vial so that the medication will flow freely.
Prior art devices for the aforementioned transfer of liquids are fraught with problems. For example, a hollow pointed shaft or needle for piercing a vial stopper, as will be explained in greater detail hereinafter, may cause coring. Coring results from the needle not only piercing the stopper but also cutting a core of stopper material with the relatively sharp edges found at the intersection of the inside diameter of the needle and the surface at the end of the needle. These cores represent a potential health hazard if they pass along with the liquid medication into the patient's body. Also, if the cores are large enough or if there are many of them, the stopper may not retain enough material to effectively seal the vial in order to prevent leakage or to protect sterility. In addition, if the device used to puncture the stopper is too large, it may damage the stopper, even in the absence of any coring, by ripping or tearing the stopper so that it no longer effectively seals the vial. Non-coring puncture devices without venting capability are also available, but are of limited use in transferring liquid to or from a vial with a pierceable stopper unless two or more of these devices are used.
Both Ogle (U.S. Pat. No. 3,941,171) and Brignola (U.S. Pat. No. 4,296,786) teach fluid transfer devices wherein most embodiments include a central body portion with large spike like projections extending outwardly from each side of the central portion. The spikes contain a pair of common longitudinally staggered parallel passages extending from the tip of one spike to the tip of the other. Since the passageways terminate at the end surface of the spikes, these devices have the potential of producing up to four cores with each vial to vial transfer. Also, the large spike size required by parallel passageways increases the potential for stopper damage and requires higher forces for penetration into the stopper. This type of device is only suitable for vial to vial transfer.
Similar to the above described inventions, Murrish (U.S. Pat. No. 2,973,758) teaches a device with a central member with two spaced needles projecting from one side thereof. One of these needles passes through the member and projects from the other side. The other needle vents to the other side of the member but does not project outwardly therefrom. Here again, for piercing and venting, two separate punctures are required, with two chances for producing cores. Also, none of the above-mentioned patents teaches a device which can be used in conjunction with a syringe or tubing with luer fittings.
Stawski (U.S. Pat. No. 3,608,550) teaches a transfer needle assembly for use in transferring liquid medication from a vial with a pierceable stopper to a plurality of syringes. Stawski shows a device with two cannulae, each having its own hub. The larger diameter cannula is used to pierce the rubber stopper and then the smaller diameter cannula slides through the larger cannula to contact the liquid in the vial. Venting takes place between the outside diameter of the smaller cannula and the inside diameter of the larger cannula. The Stawski transfer needle offers an improvement over the above-mentioned devices in that there is only one puncture which can potentially produce a core from the stopper. However, the Stawski device is primarily intended for the limited use of filling syringes and is more time-wise efficient when used with external apparatus which positions the transfer needle, but is not part of the fluid path. This external apparatus is taught by Stawski in U.S. Pat. No. 3,602,272.
Murphy (U.S. Pat. No. 2,541,272) teaches a needle for filling and exhausting ampules and, like Stawski, the Murphy needle has two hubs and one point for potential generation of cores. Murphy shows an outer sleeve which is tapered toward and anchored to the inner needle at the end of sleeve furthest from the hubs. The sleeve contains venting ports in its side and in its hub.
Choksi et al. (U.S. Pat. No. 4,058,121) teach a thermoplastic needle for injecting sterile liquid into a vial. This needle is in the shape of a plastic spike with an external vent groove running along the length of the spike. Liquid leaves the spike through two side ports therein. Choksi et al. eliminates coring by providing a pointed tip, however, the side ports, which are formed in the tapered portion of the tip, may contribute to tearing small pieces of the stopper loose as the spike moves through the stopper. Also, the apparently large cross-section can contribute to stopper damage. The external venting groove would appear to present a potential problem in that rotation of the spike along its longitudinal axis, while it is inserted in a flexible stopper, may cause parts of the stopper, along the puncture hole, to enter the groove and reduce or terminate venting capacity.
Also known is the VACUTAINER brand Multiple Sample Needle as shown in a products catalog of Becton, Dickinson and Company. This needle has two opposed cannula communicating with a central external screw thread hub. The hub is intended to be screwed into a cylindrical holder after which the first cannula, which projects outwardly from the hub, is inserted in a patient's vein. Then, an evacuated glass tube with a pierceable stopper is forceably slid into the cylindrical holder until the second cannula, which projects into the holder, pierces and passes through the evacuated tube stopper. At this point there is fluid communication between the patient's vein and the evacuated glass tube, and blood is drawn from the patient into the tube by the vacuum forces therein created. The second cannula is non-coring and has a compressed end which is cut off at an angle to the longitudinal axis of the cannula and an aperture in its side which communicates with the lumen therein. The second cannula does not have any venting structure and, because of its use, must not allow venting to the atmosphere which would reduce the vacuum forces needed to draw the blood from the patient.
The transfer of liquid to or from a container or vial with closure having an elastomeric needle penetrable stopper has been addressed by the prior art. However, there is still a need for a simple, straight-forward, reliable, easily fabricated self-venting, non-coring needle assembly which allows transfer of liquid to and from a vial with a pierceable stopper while incurring minimal stopper damage and requiring minimal penetration forces. It is also desirable that the needle assembly be operable without the use of an external apparatus which is not part of the fluid path.